This invention relates to microfilm image projection equipment of the type used in microfilm printers, readers and reader-printers and more particularly is concerned with convertible input arrangements to permit use of either roll film input or microfiche film input in a single machine.
Microfilm storage and projection systems gained their original success in the form of microfilm rolls so that today many of the early users of microfilm systems have vast libraries of microfilm rolls. More recently, the trend in the industry has been towards the use of microfiche film wherein the images are photographed in a matrix of rows and columns on a film sheet that offers greater compactness and ease of retrieval. Up until the present time, a user having libraries of both microfilm rolls and microfiche sheets has generally found it more convenient to have a separate machine for each type of film. In addition, there are many users of roll film who have not converted to microfiche film because of the additional expense and related problems of maintaining separate equipment for each type of film.
Up to the present time, the only dual purpose machines on the market have consisted of a basically roll type microfilm unit which, in addition, permits a fiche film sheet to be hand-held during projection, but this system lacks the intrinsic conveniences and advantages that have made the fiche format so popular.
There is one machine on the market which is provided with a replaceable adaptor module to permit conversion between roll format and fiche format projection systems, but such conversion requires more than two hours work by trained service personnel each time a conversion is to be made. The delay and expense associated with each conversion seriously limits the actual realization of the versatility which is intended to be achieved in such a unit.
Thus, there is a need for a microfilm projection system that may easily be converted between a roll film mode and a fiche film mode. It is also desirable that such a convertible input system accommodate the widest variety of roll film inputs so that the same machine can handle all of the existing roll film libraries while also being convertible between roll film and fiche film operation.